The invention relates to clutch actuation device, particularly for a manual transmission of a vehicle, in particular a commercial vehicle, having a clutch actuation setting device that can be placed in various positions, on the basis of which a corresponding operation of a clutch ensues.
The invention further relates to a method for controlling/regulating a clutch actuation device, particularly for a manual transmission of a vehicle, in particular a commercial vehicle, the clutch actuation device including a clutch actuation setting device that can be placed in various positions, on the basis of which a corresponding operation of the clutch ensues.
In connection with manual transmissions, clutch actuation devices of the generic type usually include clutch actuation setting devices in the form of clutch pedal devices with foot-operated clutch pedals, which are generally hydraulically coupled to an operating cylinder. The hydraulic operating cylinder is in turn mechanically coupled to a clutch operating device, for example a central clutch operator, which serves for the direct operation of a clutch. In order to reduce at least partially the force that has to be exerted by the clutch pedal for operation of the clutch, various forms of clutch servo assistance are generally used. For example, the clutch pedal device may include a so-called hydraulic master or main cylinder, which is mechanically coupled to a foot-operated clutch pedal. In this case a clutch servo embodied as an operating cylinder may be equipped with a hydraulic slave cylinder coupled to the master cylinder of the clutch pedal device. The clutch servo is also at the same time coupled to a pneumatic system, in order to provide clutch servo assistance through interaction with the slave cylinder.
Provision can also be made for clutch servo assistance virtually within the clutch pedal device. The clutch pedal device is accordingly already coupled to the pneumatic system, in particular the master cylinder of the clutch pedal device. The master cylinder is coupled to the hydraulic operating cylinder. Through interaction of the master cylinder with the pneumatic system, the clutch servo assistance is already incorporated in the clutch pedal device, which by way of the hydraulic coupling actuates the operating cylinder, in this case embodied as a hydraulic slave cylinder. In these clutch actuation devices of the prior art for manual transmissions, the use of the hydraulic actuation or coupling makes no provision for a clutch or transmission control device or transmission control electronics. In manual transmissions in commercial vehicles, the clutch is therefore operated at least partially through the use of such hydraulic systems. Their incorporation into an overall system, however, makes the overall system very costly and also expensive to service. Special functions, such as clutch monitoring functions, clutch closure detection, clutch wear optimization and clutch overload protection, for example, can be achieved only at additional cost.
The object of the invention is therefore to develop the clutch actuation devices of the generic type and methods for controlling/regulating such clutch actuation devices in such a way that the aforesaid disadvantages can be at least partially overcome and, in particular, so that a clutch actuation device of increased functionality is created.
This object is achieved by a clutch actuation device and method of controlling the device, particularly for a manual transmission of a vehicle, in particular a commercial vehicle, having a clutch actuation setting device that can be placed in various positions, on the basis of which a corresponding operation of the clutch ensues. The clutch actuation setting device is suited, as a function of its position, to generating electrical signals, on the basis of which the clutch is correspondingly operated.
Advantageous embodiments and developments of the invention are described herein.
The clutch actuation device according to the invention provides a clutch actuation setting device that is suited to generating electrical signals as a function of its position, on the basis of which the clutch is correspondingly operated. In this context, the clutch actuation setting device is preferably a clutch pedal device, which includes a foot-operated clutch pedal. It is also equally feasible, however, to use a lever for the clutch actuation setting, for example in vehicles such as motorcycles. The electrical signals may be generated by an inexpensive clutch pedal sensor, for example. The fact that the clutch actuation setting device only generates and delivers electrical signals as a function of its position means that a so-called clutch-by-wire system for manual transmission is created. The clutch actuation setting device embodied as a clutch pedal device with clutch pedal therefore delivers a purely electrical control variable. This affords the advantage, among other things, that the clutch actuation device can be mechanically simplified, since no hydraulic coupling is needed for connecting the clutch pedal device to a clutch servo or a hydraulic operating cylinder. The absence of the hydraulic coupling therefore saves both costs and the overall space required for this coupling. Where the clutch pedal device including a clutch pedal is used, it is possible by choosing a suitable spring, for example, to generate any desired counterforce characteristic for operation of the clutch pedal, since the clutch pedal device is completely isolated pneumatically and hydraulically and only has an electrical connection through the clutch pedal sensor. Inexpensive and simple electrical sensor switches can thereby be used to generate the electrical signal.
The clutch actuation device according to the invention can advantageously be developed in that the clutch actuation setting device is suited to delivering the electrical signals to a control unit, which on the basis of the electrical signals causes a pressure to be applied to a clutch operating device for operation of the clutch. This makes it possible, for example, to adjust the degree of pressure applied to the clutch operating device by way of a valve device. A clutch regulating device or clutch regulating module is preferably formed through the integration of the control unit or control electronics with the valve device including the necessary solenoid valves for actuation of the clutch operating device. This clutch regulating module can then preferably be mounted externally on the manual transmission, in particular on a clutch bell-housing. This affords greater interchangeability when servicing.
The provision of the clutch regulating module in connection with the manual transmission furthermore also makes it possible to utilize the advantages of an automated clutch control. For example, it is possible to monitor the clutch plate wear, since a clutch position can be relayed to the control unit, for example by way of a CAN bus. It is furthermore also possible to minimize the clutch plate wear. This is done by, among other things, calculating the clutch load as a function of a rotational speed, a torque, a slip etc. and by a ‘harder engagement’ of the clutch on the basis of a correspondingly defined clutch pedal position; for example when the driver of the vehicle keeps the clutch in a slipping position for an unnecessary length of time, so that a full engagement of the clutch then ensues despite the clutch pedal being only partially depressed.
The clutch regulating module can also be used to provide an overload protection. Owing to the complete hydraulic, pneumatic and mechanical isolation of the clutch pedal device from an operating cylinder, it is possible to achieve an adjustment of the clutch pedal characteristic, for example through electronic optimization of the clutch characteristic curve.
In addition, all diagnostic functions can be performed by the clutch regulating module. Communication with other vehicle control modules is also possible, for example communication with a control module of an electronic braking system; in this case this communication may consist, for example, in opening the clutch in the event of an antilock braking mode instituted by an ABS system, thereby interrupting a power flow in a drivetrain in the event of ABS control. Similarly communication may also be provided between ESP electronics or an ESP control unit for the execution of an electronic stability program, which serves to interrupt the drivetrain in the event of ESP control. Communication can likewise be established with ASC electronics or an ASC control unit for acceleration skid control, in which, for example, an ‘automated’ starting is permitted with a slipping clutch even when the clutch pedal is not being operated, in order to prevent wheel spin on the drive wheels of the vehicle.
In addition it is also possible to achieve an interaction with a halt brake system or to combine the control/regulation through the clutch regulating module with a so-called hill-holder function. Thus, when bringing the vehicle to rest on an incline, a braking force is maintained without the need to operate a parking brake or a handbrake of the vehicle. At the same time an automated disengagement of the clutch can be undertaken, if the driver fails to do this, in order to prevent stalling of the internal combustion engine of the vehicle. The vehicle is then driven off again by operating an accelerator pedal, the clutch being automatically engaged. An interaction is also possible with a transmission control connected to a gearbox servo, which permits release of the gearbox servo (power-assisted gearshift) only when the clutch is operated, for example.
Further advantages also accrue in connection with the clutch operating device embodied as an operating cylinder. Thus the operating cylinder may be fitted externally to a clutch bell housing and preferably integrated into the clutch regulating module. Alternatively, the operating cylinder may also be designed separately, for example as a central clutch operator. A travel or position sensor is preferably provided directly in the operating cylinder. A separate evaluation unit for this sensor may be arranged either in the operating cylinder or also on the clutch regulating module, for example.
In order to enhance the reliability of such a clutch-by-wire system, redundant components can be incorporated into the clutch actuation device. In particular, for example, the clutch pedal device may deliver two mutually independent electrical signals for the clutch pedal position or clutch pedal setting, for example via two different electrical lines from two corresponding sensors. Four electrical lines may equally well be provided, in order to provide the clutch regulating module with two supply voltages and two ground connections. This serves at least greatly to reduce any probability of failure on the part of the clutch regulating module. With regard to the adjustment of the pressure applied to the clutch operating device, the valve device may include redundant solenoid valves both for ventilation and venting of the clutch operating device. The operating cylinder may likewise supply the clutch regulating module with two mutually independent electrical signals for the release travel of the clutch via two electrical lines.
In addition, the clutch actuation device according to the invention can also be embodied so that a valve device is provided, which is suited to applying a pressure to the clutch operating device. For example, the valve device may include two ventilation valves, connected in parallel, for ventilation of the clutch operating device, one of the two solenoid valves having a large flow cross section and the other having a small or smaller flow cross section. The clutch operating device can therefore be ventilated with different volumetric flows. Similarly, two solenoid valves having different flow cross sections that are connected in parallel are preferably also used for venting the clutch operating device. These solenoid valves for ventilation and venting are, in particular, embodied as 2/2-way valves.
The clutch actuation device according to the invention may further be embodied in such a way that the clutch actuation setting device is suited to generating further electrical signals as a function of its position, and delivering these further electrical signals to a further control unit. The further control unit is suited to delivering the further electrical signals to the control unit. Provision of the further control unit serves further to enhance the reliability of the clutch-by-wire system. In this context, the clutch pedal device preferably delivers two mutually independent electrical signals, the first signal being supplied to the control unit, which is assigned to the clutch regulating module, for example, whilst the second signal is supplied to the further control unit, for example via a CAN bus. This further control unit may in particular be any vehicle control module, which in turn delivers the further signals to the control unit assigned to the clutch regulating module, for example likewise via a CAN bus. Both the control unit of the clutch regulating module and the further control unit may obviously be in communication with any vehicle control modules via the CAN bus. In this case, for example, it is possible to separate the drivetrain of the vehicle through the clutch when the antilock brake control is activated by the ABS system.
It is furthermore possible, particularly when a system failure of the clutch actuation device is registered, for the drivetrain of the vehicle to be correspondingly shifted to an idling state either manually via the gearbox or preferably electronically on the basis of the corresponding control module, if the manual transmission is designed to allow this. In this context, it may be particularly advantageous for the manual transmission, where necessary, to initiate semi-automatic running if the manual transmission is designed to allow this. For example, on operation of the gearshift lever, a clutch operation may be triggered via a sensor so that the driver no longer needs to operate the clutch pedal when shifting gear whilst underway. In this case the clutch pedal is only needed for driving off and maneuvering.
The clutch actuation device according to the invention is preferably embodied so that a travel sensor is provided, which serves to detect a position of the clutch operating device, and on the basis of the signals from which it is possible to control/regulate the clutch operating device.
In this context, the clutch actuation device according to the invention can be developed in such a way that a pressure sensor is furthermore provided, by which the position of the clutch operating device can be determined, at least in the event of a failure of the travel sensor, and on the basis of the signals from which it is possible to control/regulate the position of the clutch operating device. Even in the event of a failure of the position or travel sensor in the clutch operating device, this will allow an emergency control by way of the pressure sensor incorporated in the clutch regulating module, for example. However, the pressure sensor may equally well be provided in order to improve the control quality through interaction with the travel sensor.
The clutch actuation device may furthermore be embodied so that one or more of the following components are accommodated in a housing in a mechatronic unit: the control unit, the valve device, the travel sensor, the pressure sensor, and the clutch operating device.
The method according to the invention operates in that the clutch actuation setting device generates electrical signals as a function of its position, on the basis of which the clutch is correspondingly operated. In the same or a similar way, this affords the advantages explained in connection with the clutch actuation device according to the invention, so that in order to avoid repetition reference will be made to the corresponding descriptions in connection with the clutch actuation device according to the invention.
The same applies analogously to the following preferred embodiments of the method according to the invention, so that again in order to avoid repetition reference will be made to the corresponding descriptions in connection with the clutch actuation device according to the invention.
The method according to the invention can advantageously be developed in that the clutch actuation setting device delivers the electrical signals to a control unit, which on the basis of the electrical signals causes a pressure to be applied to a clutch operating device for operation of the clutch.
The method according to the invention can furthermore be embodied so that a valve device applies pressure to the clutch operating device.
In addition, the method according to the invention may be embodied in such a way that the clutch actuation setting device generates further electrical signals as a function of its position and delivers these further electrical signals to a further control unit, the further control unit being suited to delivering the further electrical signals to the control unit.
The method according to the invention can furthermore be embodied so that a position of the clutch operating device is detected by a travel sensor, and the position of the clutch operating device is controlled/regulated on the basis of signals from the travel sensor.
In this context the method according to the invention can be developed in such a way that by use of a pressure sensor the position of the clutch operating device can be determined, at least in the event of a failure of the travel sensor, and the position of the clutch operating device is controlled/regulated on the basis of the signals from the pressure sensor.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.